In the last two years, the world has awakened to the AIDS tragedy and what it takes to bring it under control, but there is no indication that the epidemic is leveling off worldwide and strategies known to prevent the spread are still grossly underused, the U.N.'s AIDS chief said Sunday.

More than 15,000 people from around the world have gathered in Barcelona to spend a week looking for solutions to an epidemic that now infects 40 million worldwide, more than half of them in Africa.

Scientific discoveries in HIV and AIDS seem to be merely incremental, experts in the field said Sunday at the start of the high-profile 14th International AIDS Conference. New drugs that do the same thing -- but slightly better -- are emerging, but there's no vaccine or blockbuster treatment around the corner.

"From a historical perspective, we are still in the early days of the epidemic," said Dr. Peter Piot, executive director of the U.N. AIDS program. "There are no indications that the AIDS epidemic is leveling off, not even in the most affected countries."

In China, the former Soviet Union and other countries in Asia, the virus is spreading swiftly, Piot said. In Russia, reported cases have increased by more than 15 times in three years.

"The major challenge we have is growing in scale -- expanding to more regions the strategies known to work -- and for those countries where HIV is starting to expand, to make sure, by intervening early enough, that they don't go the way that Africa has gone," Piot said.

"AIDS is starting to destabilize entire nations in Africa. A destabilized part of the world, however far away it may be from where you are is having an impact on your own country," he said.

Last year, 1 million children in Africa lost their teacher because of AIDS, Piot said.

"We will have to change some of the rules of the game. Countries like Botswana, which has done very well in terms of economics and good governance -- in Africa it's a success story -- risk becoming what I would call 'undeveloping' because of AIDS," Piot said.

Botswana is not eligible for international development funding because it has done too well. But the AIDS problem is so severe, it is threatening to wipe out those gains.

Piot said eligibility should not only take into account gross domestic product but also the AIDS burden.

Although the epidemic continues to grow, progress has been made since the last international AIDS conference two years ago in Durban, South Africa.

"Durban was the beginning of a wake-up call and since then a lot of things have happened," Piot said. "We are moving into an era where AIDS has become a top global issue."

"That will was not there six years ago. It started appearing in many countries over the last two years," Piot said. "In March I met with the patriarch of the Russian Orthodox Church. The fact that he was willing to see me ... this would have been impossible before."

The change is evident not only in the rhetoric of political leaders around the world, but also in the amount of money being funneled to AIDS activities, he said.

There has been a sixfold increase in funding for AIDS prevention programs in developing countries since 1998, with the most impressive gain occurring in the last two years, Piot said.

About $2.8 billion will be spent on AIDS prevention programs in low- and middle-income countries this year. However, those countries need $10 billion a year for AIDS, he said.